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Naltrexone: Cost, Dosage, and Side Effects

Naltrexone is a medication commonly used to help treat alcohol or opioid dependence.1 When used safely, it can help people remain abstinent by blunting the pleasurable sensations of these substances, as well as by reducing cravings for them.

This article answers common questions about naltrexone, including:

  • How does it work?
  • What are the side effects?
  • How is naltrexone administered?
  • Does it interact with foods or other medications?
  • How much does Naltrexone cost?
  • Is it effective?

What Is Naltrexone?

Naltrexone is a medication approved by the Food and Drug Administration (FDA) for the treatment of alcohol and opioid dependence.2

The National Institute for Health and Care Excellence recommends naltrexone for people who are fully detoxed from alcohol or opioids and are highly motivated to remain abstinent.1 Naltrexone is also sometimes used off-label to treat opioid and nicotine withdrawal as well.2

Although naltrexone is a helpful medication, it is not a cure for alcohol or opioid dependence.4 To be effective, naltrexone must be combined with other psychosocial therapies such as cognitive behavioral therapy or motivational interviewing, or with a 12-step program such as Alcoholics Anonymous or Narcotics Anonymous.5

How Does Naltrexone Work?

Naltrexone falls into a class of medications known as mu-opioid receptor antagonists.2 Signaling within the brain as well as between the brain and body takes place with the aid of neurotransmitters. These chemicals are released from specialized cells throughout the nervous system and exert their effects by binding to different receptors.

When opioid-type neurotransmitters (e.g., endorphins) bind with the mu-receptor, a signal is sent that alters pain perception. This interaction may trigger additional signaling that leads to pleasurable, relaxing, or euphoric sensation.

You are teaching your brain that alcohol and opioids are no longer rewarding.

Naltrexone works by blocking these mu-opioid receptors so that other substances cannot attach to them.1 When the mu-opioid receptors are blocked, these signaling mechanisms are altered. The perception of pleasure that might otherwise accompany the use alcohol or opioids is muted, as is the chemical reinforcement of their continued use.3

If you use naltrexone over a period of time, you are actually teaching your brain that alcohol and opioids are no longer rewarding.1 This, in turn, helps to reduce cravings and prevent a relapse.1

Who Can Prescribe Naltrexone?

Physicians and nurse practitioners can prescribe naltrexone.4 In some states, physician assistants and psychologists can prescribe it as well.4

While your primary care provider is able to prescribe this medication, it is best to receive expert care from an addiction medicine specialist, namely a psychiatrist or a psychiatric nurse practitioner at either a psychiatric or an addiction clinic.4

Naltrexone should only be taken under the direct supervision of a healthcare provider.

Naltrexone Side Effects

Common naltrexone side effects can include:1
  • Abdominal pain and cramps.
  • Anxiety.
  • Headache.
  • Joint and muscle pains.
  • Nausea and vomiting.
  • Sleep problems.
  • Tiredness.

Less common side effects include:1

  • Chills.
  • Delayed ejaculation.
  • Depression and irritability.
  • Diarrhea or constipation.
  • Dizziness.
  • Feeling energetic.
  • Loss of appetite.
  • Skin rashes.
  • Thirst.

Some people have experienced suicidal ideation while taking naltrexone.1 People with a history of suicidal thinking may be at increased risk of this side effect.1 If you begin to feel down, depressed or hopeless, speak with your healthcare provider.

Allergic Reactions to Naltrexone

As with any new medication, you may be at risk of developing an allergic reaction to naltrexone.1 The following signs of an allergic reaction to naltrexone can include:1

  • Sudden, raised red spots on your body.
  • Itching.
  • Stomach pain.
  • Nausea.
  • Feeling lightheaded, weak, confused and restless.
  • Vomiting.
  • Swelling of the throat, mouth, lips or tongue.
  • Difficulty breathing.

If you develop an allergic reaction, seek medical attention immediately and discontinue the medication.

Long-Term Effects of Naltrexone Use

Large doses and long-term use of naltrexone can hurt your liver, especially when naltrexone is combined with alcohol.1 Contact your healthcare provider if you develop any of the following symptoms, which might indicate liver damage:1

  • Dark urine.
  • Excessive fatigue.
  • Light-colored bowel movements.
  • Loss of appetite.
  • Pain in the upper right area of the abdomen that lasts longer than several days.
  • Unusual bruising or bleeding.

How Is Naltrexone Administered?

Naltrexone comes as a tablet or as a gluteal intramuscular injection.2 You and your healthcare provider can discuss which form works best for you. Both forms of naltrexone will begin blocking the mu-opioid receptors in your brain shortly after the first dose.2

Most courses of naltrexone therapy are carried out for a minimum of 3 months.4


The tablet form of naltrexone comes in 25 mg, 50 mg, and 100 mg doses.2 The usual starting dose of oral naltrexone is 50 mg per day. But this may range from 25 mg to 100 mg depending on your situation.2

Often, healthcare providers will give you an initial dose of 25 mg to test your tolerance of the medication’s side effects and make sure that you do not have an allergic reaction to it.1

If you miss a dose, wait until your next scheduled dose. Never take extra doses to make up for a missed dose.2


Sometimes healthcare providers will prescribe a 380 mg once per month intramuscular injection of naltrexone.2 This method can cause some discomfort at the injection site. However, you do not have to remember to take a tablet every day.1 You will need to wear a warning bracelet because this form of the medication can block the pain relieving effects of opioids, which can lead a person to take more of the drug and thus increase the potential for serious injury or even death.11

If you miss a dose, reschedule your injection appointment as soon as possible.

Mixing Naltrexone

Naltrexone blocks the effects of any opioid-containing drug or medication, which includes some cough and cold remedies, antidiarrheal preparations and opioid analgesics.2 While taking naltrexone, avoid alcohol because it will greatly increase your risk of liver damage.1

Before starting naltrexone, tell your healthcare provider if you are taking any of the following medications:2

  • Droperidol.
  • Fentanyl.
  • Leflunomide.
  • Lomitapide.
  • Mipomersen.
  • Teriflunomide.

Naltrexone can cause opioid withdrawal symptoms in those who are opioid-dependent. Therefore, you should be detoxed from opioids for at least 7 days before taking your first dose.1 Be honest with your healthcare provider about your most recent use to ensure a safe experience. Some clinicians may use a urine drug screen or skin test to verify that you are detoxed before beginning naltrexone treatment.4

Never use heroin after having recently taken naltrexone. The medication lowers a person’s tolerance to heroin, which increases the risk of death from just a small amount.1

If you believe you or someone you love is experiencing the effects of an overdose, call 911 immediately.

American Addiction Centers maintains a strong partnership with a large group of insurance companies at our addiction treatment facilities. Start the journey to recovery and find out instantly if your insurance provider may be able to cover all or part of the cost of rehab and associated therapies.

How Much Does Naltrexone Cost?

The cost of naltrexone differs by insurance type, but the tablet form is often covered.2

  • Oral form. The price of oral naltrexone usually varies from $25 to $60 per month.2
  • Injectable form. The naltrexone injection cost is significantly more expensive, usually ranging from $700 to $1,100 per month.2

Sometimes insurance companies will require your healthcare provider to submit a prior authorization before they will cover naltrexone.4 A prior authorization requires you to meet certain criteria. For example, you might have to demonstrate that you are fully abstaining from alcohol and opioids and that you are also participating in psychosocial treatment.4

How Effective Is Naltrexone?

Several studies have looked at the effectiveness of naltrexone. Overall, it has shown some success in helping people control their alcohol and opioid use.

  • Based on a 2010 systematic review, naltrexone appears to reduce heavy alcohol consumption and reduce drinking days in those suffering from alcohol dependence.7
  • A 2013 study published in the Journal of the American Medical Association found that naltrexone can reduce alcohol use in people with comorbid post-traumatic stress disorder and alcohol dependence.8
  • A Cochrane Systematic Review in 2015 found that naltrexone reduced re-incarceration rates in people with a history of both opioid abuse and criminal activity.10
  • A 2011 Cochrane Systemic Review concluded that oral naltrexone was no more effective than psychotherapy or buprenorphine in treating opioid dependence.9 This study also found that oral naltrexone did not increase rates of abstinence from opioids following a full detoxification.10

Frequently Asked Questions on Naltrexone

Is Naltrexone Addictive?

Naltrexone is not physically or psychologically addictive.1 It can reduce cravings for alcohol and opioids, but it should not interfere with other pleasurable experiences.2

Can You Drink Alcohol While You’re Taking Naltrexone?

You should not drink alcohol when taking naltrexone.1 Combining alcohol with naltrexone can damage your liver.1

Can Naltrexone Get You High?

You will feel neither “high” nor “down” when taking this medication.1 You will probably not notice much of an effect beyond mild side effects.1

Get Help for Alcohol or Opioid Addiction

If you or someone you know needs more information about alcohol or opioid addiction treatment, please call the compassionate admissions navigators at American Addiction Centers toll-free at . We can verify your insurance, determine treatment coverage, and help you find the right treatment for your needs.